Automatic variable pitch propeller



Dec. 18, 1934. c. w, LAMBERT 1,935,041

AUTOMATIC VARIABLE FITCH PROPELLER Filed Feb. 25, 1934 4 Sheets-Sheet l .fm/farma.

WMM

Dec. 18, 1934. c, w. LAMBERT 1,985,041

AUTOMATIC VARIABLE FITCH PROPELLER l Filed Feb. 23, 1934 4 Sheets-Sheet 2 Dec. 18, 1934. c. w. LAMBERT AUTOMATIC TARIABLE FITCH PROPELLER Dec. 18, 1934. c; w. LAMBERT 1,985,041

AUTOMATIC VARIABLE FITCH PROPELLER Filed Feb. 23, 1954 4 sheets-sheet 4 Patented Dec. l18, 1934 UNITED STATE-s.

PATENT y OFFICE' The `invention relates to automatic variable pitch propeller and is an improvement of ap' plicants Patent #1,913,123 dated June 6, 1933. l The` improvement necessitates only one comr pression spring instead of two balanced control springs, and vreduces the travel of the pressure plate. AAnother feature is the use of power for the clutching or gear shifting means, `instead of coupling the gear shifting device directly to Athe control plate. -This feature isan improvement of the electromagnetic'gear shift of Patent apt-1,924,061 dated Aug. 22, 1933,` the present inventionnembodying improvements of practical fdesign. i f

Sirnilarparts are numbered the same in all 'figures of the drawings.

Figxl Iis a longitudinal cross-Section of the automatic 4control device. i

` `matic control shown in Fig. 1.

I Fig. 3` is a detail drawing, partly in section, of the automatically controlled, powered, gear shift shown inFigs. 1 and 2. Fig. 4 is a transverse showing of the low speed side of the `reduction gearing to the propeller 4,blade shanksylooking rearwardly;'-` while,

Fig. `5 is a transverse `showing of Vthe high fspeed side, of the Vreduction gearing, looking forwardly. ,The twelve short shafts of the re- 130 duction gearing are enclosed within the hub, surrounding the 'power shaft and the barrels ,of huh-,corresponding to the twelve edges of a cube. The form shown in Fig. 4 is for a 4four bladed propeller, but any arrangement of the reduction gearing can be used without departing from the Aspirit of thel invention. For a two bladed propeller, two ,of the slow speed 'worm gears of Fig. 4, as 66 and 76,wouldbe omitted. Fig. 6 is a longitudinal view, partly in section, of the power shaft and propeller. hub, showing the reduction gears for one blade, and

the connection to the automatic control of Fig.

1, of Awhich Fig. 6 is a continuation.

Fig. 7 is a transverse" showing of the star Wheel and the nonrotative' lugs vagainst'which it reacts.

In the detailed descriptionmstarting with 6 andthen later progressing to Fig.` `1, in` Fig.

50, 6, 1 is the main power shaft,l 2 is thepropellerhub securedV to shaft 1v which projects from `crank case 3, to -which is secured the non- Arotative bracket 30 with the lugs 31` and 32, which cause star wheel 29 to rotate fin reverse 355 directions for the purposeof rotatingthe blades Fig. 2 is a transverse cross-section of the auto lis `ing shaft 28 and with it star wheel 29.y Star wheel- 29 furnishes power to the reduction gears for the purpose of rotating the blades to posi- .191% secureto plat-,913, `may be contacted into positions of decreased or increased pitch. Star wheel 29 is secured to shaft 28 which has a limited longitudinalmovement. Shaft 28v and tube 23 turnf'together; shaft-28 being splined intube 23 oriwhieh bevel gear v'25 is secured 5 and meshes with bevel gears' 26 and 27, see Fig.

`5. To tube 23 is also secured worm gear 24 jwhich meshes with gears 63 and 64' on slow f speedfshafts and 65, on which slow'speed worm gears 81 and 66, see Fig. 4, mesh with 10 `gear similar to 82, by which the motion is transmitted to splined hub or spindle 83 and to the Ashank of a propeller blade.

- Shaft 85 rotates independentlyof tube 55, and

'wheel 34` is'always in intermittent contact with `lug 31. This furnishes power for shifting shaft 428 and starr wheel 29 at any time whenshaft rotating, as shown in connection with Fig. 20

` Star wheel 84 by continuous intermittent contact with lug 3,1, furnishes power to gear 35', and this power is used only for longitudinally shifttionsof greater or lesser pitch. "Star ywheel 29 contacts either lug 31 lor 32 only `when changes `of air-speed, through vthe automatic control, 30

necessitate corresponding changes-of blade pitch. At all other" times during periods of` constant air speed,ystar` wheel 29 contactsneither lug 31 Inor 32; `and tube 23 and they reduction rgearsA do notrotate. n '35 j `InHFig.V 1- isshown afragment'of hub 2'which is vsecuredvto power shaft 1 by nut 4. Shaft lextension 5 and frame' are secured to shaft 1 `byfspaced-screws 8 8. Sliding extension 6 `in Vshaft extension 5 is secured to frame 93 of pressure plate 9 which has supporting webs 'l0-+10 on `which flanges slide in grooves 11-11 sof frame 7. Stops -95 on webs 10-10 may v contact stops 96-96 on frame 7 to prevent excessive movement of plate 9, Figs.1and.2. T45

`'Io extension 5 is secured flanged collar v22, on `which gear 20 is free to rotate meshing with .issecured tube 19 which has internal threads 18 cooperating with external threads on nut '1.7

One end'of compression spring 12 presses against nut 17 and the other end against control plate 13. The ends of tubes to the right.

ytion but intermittent `in speed and time. ,star Wheel 84 is in contact with lug 31, gear 35 see Figs. 1--2-3, which are secured to gear 35 which is loose on shaft 28 between stops `4 5 and 46 which are secured to shaft 28. Gear 35 rotates independently of shaft 28.

To shaft 28 is secured grooved 33 which is contacted by notched bar 34- which slides vertically in guides on frame 7 and is held in contact with grooved stop 33 by compression spring97.

\ Gear ,35 rotates always in the same direction,

but shaft 28 rotates in reverse directions. Gear 35 meshes with large gear 8,8 which is loose on tube 19, locknuts 91 preventing displacement by end motion. Gear 88 meshes with gear 87 on Vshaft 85,A on which brake wheel 89 is also secured. Drag brake makes only sufcient conrtact with brake wheel 89 to prevent spinning of Plate 13 is secured to frame 93fby pins 94-94 which have :alimited longitudinal freedom of movement by sliding through frame 7. Plate 13 remains` in the `neutral position Where shown in Fig, 1, only solong `as the air pressure on plate A9 vbalances the pressure of spring 12 on plate 13 Increase of airspeed moves plate 13 jto rthe left, `decrease of airspeed moves plate 13 The movement of plate 13 and plate; 9` is transmittedto racks 41 and 42 which control the position of gear 35 and star wheel 29 the reaction Qfeams 4 3 and 44 on the stepped racks 42 vand 414 respectively.

.,whenfgear 35,1 is in the neutral position as yshown in Fig. 1, and plate 13 is also in the neutral or balanced position, cams 43 Vand 44 just pass between the lower steps of the racks 42 and 41. Movement of plates 13 and 9 toward the left, caused byan increase or" airspeed, lowers rack42 `and raisesrack 41. Cam 43 contacts the upper step of rack 42 and shifts gear 35 and shaft 28 to the right. Star wheel 29 now contacts` lug 31 and rotates the reduction gears in adiretion to increase theblade pitch. At the same time nut 17 moves to the right compressing Aspring 12 when the pitchof the propeller blades is increasing, and Vice versa.I The resultl is always to restore plate 13 to the neutral position and disengage gear 29 from either lug 31 or 32.

Thismeans that the tendency is for the angular .pitch-of the blades to closely follow any change of airspeed. The `position of nut 17 is a relative measure of the blade pitch at any instant.

The air pressure on plate 9 is likewise a measure of the airspeed.

The action of gear 35 is continuous in direc- When rotates one sixth of a revolution. This movement takes place when star Wheel'29 is on the opposite side of shaft, 1 frombracketO; or Yin other words When wheel 29 is out of contact with either lug 31 or 32. This is theVv instant when cams 43 and 44pass the racks 42 and 41 and any shifting action takes place. This prevents annular stop jamming of Wheel 29 against the side of either lug 31 or 32.

Fig. 2 shows a broken cross-section of the control mechanism in the region of gears 35 and 87. 7 is the frame, 9 the rearwardly extending skirt of the pressure plate. 6 the centrally located sliding shaft extension. 5 the shaft eX- tension, 12 the compression spring, 15-15 the pitch limiting rods, 92-92 the high pitch limiting stops, 88 the large gear loose `on tube19, 35A the shifting gear.

In Fig. 3, gear 35 is shown and the relative position of stepped racks 41 and 42, and the cams 43 and 44 which are secured to gear 35.

In Fig. 4, looking rearwardly, it will be noticed that the slow speed worm gears 66-71- 76-81 are mounted in the front side of the hub, each' acting on a-gear which is coaxial with a blade shank (as gear 82 of Fig. 6). The motion is received from 4 worm gears 24-68--73-78 1, While shafts 47 and 57 `turn outward; and vice versa. Tubes 23 and 55 turn clockwise while shafts 50 and 60 turn counterclockwise; and

viceversa,

1n Fig. 4, worm gears 24 and 73 and gears 63- 64-72--74 have `right hand threads;A and worm gears 68 and 78 and gears 67-69-77-79 have left hand threads.

Concerning the speed of operation of the automatic variable pitch, the reduction gear can be of vsuch ratio that at normal-engine speed, the

time required to change from minimum to maxlimumlolade pitch, or vice versa, is about ythe same as the least time required to change the air speed from lmaximum to zero, or vice versa, while in the air, say 6 to 10 seconds. With slower changes of air speed, the sensitive auto- .matic control causes the gearing to follow by short, intermittent periods of action, any appreciable changes of airspeed.

Stalling is prevented. The engine'and'blades always operate at full efficiency regardless of airspeed.

The automatic variable pitch, as shown,v is entirely mechanical, simple, balanced, rugged,

efcient; shortens takeoff run; increases climbing angle and climbing speed; gives higher maximum airspeed; increases payload, revenue,

and safety.

I claim; v 1. An automatic variable pitch propeller,com

prising; a movable pressure plate cooperating with a compression spring; a rotatable pro- `peller blade shank; a splined nut cooperatively f.

associated with said shank and said spring; pitch changing means comprising a nonrotating member and a cooperatinglrotating member; 'and reversible gearing coope-rating with `said blade shank and said nut; control means,`

comprising independently powered cams and cooperating cam followers cooperatively .associated with said pressure plate andsaidgearing; ,means limiting the extent of action of said pitch changing-means.

Gears 48 and 5l do not mesh with each: other. .Shafts 62 and 52 turn in toward shafty 2. A propeller shaft; a hub secured to said shaft; spaced rotatable propeller blade shanks cooperating with said hub; means for rotating said shanks in reverse directions relatively to said hub, comprising a splined nut and compression spring; means for measuring the eX- tent of rotation of said shanks relatively to said hub; airspeed measuring means comprising a movable pressure plate and a cooperating compression spring; control means comprising gear control cams powered independently of said shank rotating means, cooperating with said airspeed measuring means and said shank rotating means.

3. A propeller shaft; a hub secured to said shaft; a rotatably mounted propeller blade shank cooperatively associated with said hub; means for rotating said shank; a movable pressure plate; a compression spring cooperating with said pressure plate; a movable nut cooperating with said shank rotating means and said compression spring; cams powered independently of said shank rotating means cooperating with said pressure plate for controlling the action in reverse directions of said shank rotating means; means cooperating with said nut for limiting the movement of said pressure plate.

4. In a propeller mechanism, a rotatable splined spindle coaxial with a propeller blade hub Y barrel, rotating means comprising reduction gears cooperating with said spindle, reversing means cooperating with a source of power and said gears, a splined nut cooperating with said gears, a compression spring cooperating with said nut, a pressure plate cooperating with said spring, limiting means cooperating with said nut and said plate, control means cooperating with said plate andsaid reversing means.

5. Means for rotating in reverse directions rotatably mounted spaced propeller blades by intermittent application of controlled power to said means, control means comprising a movable pressure plate and a cooperating compression spring, reversing means cooperatively associated with said control means, said reversing means cooperating with said blade rotating means during the interval of disassociation from said intermittent controlled power.

6. In a propeller mechanism, a non rotating member, a power shaft, a hub thereon, spaced rotatable blades secured thereto, reversible gearing cooperating therewith, a movable plate, a compression spring, a threaded tube, a splined nut, a reversing means cooperating with said non rotating member and said plate and said gearing, limiting means cooperating with said nut and said plate, substantially as specified.

CHANDLEY WILLIAM LAMBERT. 

